Microlithographic projection exposure apparatuses are used for the fabrication of microstructured components such as, for example, integrated circuits or LCDs. Such a projection exposure apparatus typically has an illumination device and a projection objective. In the microlithography process, in general, an illumination device is used to illuminate a mask (reticle) whose image is then projected onto a substrate, such as a silicon wafer, via a projection objective. Usually, the substrate is coated with a light-sensitive layer (photoresist) which is arranged in the image plane of the projection objective so that the mask structure is transferred to the light-sensitive coating of the substrate.